A holding arrangement of the kind referred to above is disclosed in U.S. Pat. No. 6,523,796. There, a surgical microscope stand is described having a first link and a second link which are articulately connected at a common pivot base. The first and second links form a parallel link construction in that they are connected at their front ends by a front link. A surgical microscope is mounted on this front link. A load torque occurs at the pivot base and is caused by a load taken up on the parallel link construction. To compensate this load torque, a force storage element is provided in the parallel link construction and this storage element is configured as a linear spring. This force storage element is pivotally connected to one of the carrier links of the parallel link construction and applies a tension or pressure force to the pivot base in order to hold the surgical microscope, which is accommodated on the parallel link construction, in a floating state.
U.S. Pat. No. 5,213,293 discloses a carrier arrangement for medical-optical equipment wherein a force storage element is provided for generating a linear force with this force storage element being in a frame arm of a surgical microscope stand. The force storage element is supported on the pivot base of the frame arm in a guide in order to compensate a changing force of the force storage element which is dependent upon the stroke.
U.S. Pat. No. 5,492,296 discloses a surgical microscope stand wherein a surgical microscope is accommodated on a stand and is movably accommodated via rotational joints on a pivot axis and a tilt axis. Torsion springs are assigned to the rotational joints for balancing a load torque caused in the rotational axis and tilt axis by the surgical microscope. The pretensioning of the torsion springs can be adjusted.
European patent publication 0 628 290 discloses a surgical microscope stand wherein a surgical microscope is carried by a parallel link construction which is supported on a stand console with a pivotal support point so as to be pivotally movable. Balancing masses are provided on the surgical microscope stand to balance a load torque occurring at the parallel link construction. The balancing masses compensate the weight of the surgical microscope accommodated on the parallel link construction.